The Change Of Monoamine Neurotransmitters In The Brain Stem During Adaptation Progress Of Seasickness

Objective The study aims to observe the change of monoamine neuratrasmitter in the brain stem during seasickness and after adaptation so as to explain the symptom and reduce the incidence of the seasickness and render the foundation of the diet intervention. Method 24 SD male rats were divided into the control group, seasickness 1d group, 7d group, 14d group. The severity of their seasickness was identified according to their kaolin consumption. Open-field test was used to valuate the mental activity. The changes of the expression of Fos protein in brain stem were observed by immunohistochemical ABC staining method. 5-HT, NA, DA contents in brain stem of rats were measured by the fluorometic analysis. The changes of the 5-HT expression in brain stem were observed by immunohistochemical ABC staining method. Result Compared with the control group, the kaolin consumption of seasickness 1d group increased markedly. Compared with seasickness 1d group, the consumption of kaolin reduced markedly in seasickness 7d group and 14d group. Compared with the control group, the OFT scores decreased significantly in seasickness 1d group. Compared with the control group, the number of Fos-positive neurons increased markedly in 1d and 7d group. The number of Fos-positive neurons in 14d group were not different from the control group. Compared with the control group, the concentration of NA in 1d group decreased markedly. Compared with 1d group, the content of NA increased markedly in 14d group and return to the control level. Compared with the control group, the concentration of 5-HT in 1d, 7d and 14d group increased markedly. Compared with 1d group, the concentration of 5-HT in 7d and 14d group decreased gradually in sequence. Compared with 7d group, the concentration of 5-HT in 14d group decreased markedly. There was no difference in dopamine concentrations among the four groups. Compared with the control group, the number of 5-HT immunoreactive neurons in raphe obscurus nucleus (Rob), raphe magnus nucleus (RMg) and gigantocellular reticular nucleus (Gi) increased markedly in Id group. No difference was observed between 14d group and control group in the number of 5-HT immunoreactive neyrons in Rob, RMg and Gi. Conclution The role of NA, 5-HT in the brain stem may be important during motion sickness and adaptation. The function of DA in the development of seasickness and adaption may be unimportant.